• ALGAE
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• v.36 no.4
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• pp.315-326
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• 2021

Ion channels are membrane protein complexes mediating passive ion flux across the cell membranes. Every organism has a certain set of ion channels that define its physiology. Dinoflagellates are ecologically important microorganisms characterized by effective physiological adaptability, which backs up their massive proliferations that often result in harmful blooms (red tides). In this study, we used a bioinformatics approach to identify homologs of known ion channels that belong to 36 ion channel families. We demonstrated that the versatility of the dinoflagellate physiology is underpinned by a high diversity of ion channels including homologs of animal and plant proteins, as well as channels unique to protists. The analysis of 27 transcriptomes allowed reconstructing a consensus ion channel repertoire (channelome) of dinoflagellates including the members of 31 ion channel families: inwardly-rectifying potassium channels, two-pore domain potassium channels, voltage-gated potassium channels (K_v), tandem K_v, cyclic nucleotide-binding domain-containing channels (CNBD), tandem CNBD, eukaryotic ionotropic glutamate receptors, large-conductance calcium-activated potassium channels, intermediate/small-conductance calcium-activated potassium channels, eukaryotic single-domain voltage-gated cation channels, transient receptor potential channels, two-pore domain calcium channels, four-domain voltage-gated cation channels, cation and anion Cys-loop receptors, small-conductivity mechanosensitive channels, large-conductivity mechanosensitive channels, voltage-gated proton channels, inositole-1,4,5-trisphosphate receptors, slow anion channels, aluminum-activated malate transporters and quick anion channels, mitochondrial calcium uniporters, voltage-dependent anion channels, vesicular chloride channels, ionotropic purinergic receptors, animal volage-insensitive cation channels, channelrhodopsins, bestrophins, voltage-gated chloride channels H⁺/Cl^- exchangers, plant calcium-permeable mechanosensitive channels, and trimeric intracellular cation channels. Overall, dinoflagellates represent cells able to respond to physical and chemical stimuli utilizing a wide range of G-protein coupled receptors- and Ca²⁺-dependent signaling pathways. The applied approach not only shed light on the ion channel set in dinoflagellates, but also provided the information on possible molecular mechanisms underlying vital cellular processes dependent on the ion transport.

• The Korean Journal of Physiology and Pharmacology
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• v.4 no.6
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• pp.427-437
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• 2000

The early studies of cardiac and smooth muscle cells provided evidence for two different calcium channels, the L-type (also called high-voltage activated [HVA]) and T-type (low-voltage activated [LVA]). These calcium channels provided calcium for muscle contractions and pace-making activities. As might be expected, the number of different calcium channels increased when researchers studied neurons and the identification of the neuronal calcium channels has proven to be much more difficult than with the muscle calcium channels. There are two reasons for this difficulty; (1) a larger number of different calcium channels in neurons and (2) many of the different calcium channels have similar kinetic properties. This review uses the N-type calcium channel to illustrate the difficulties in identifying and characterizing calcium channels in neurons. It shows that the discovery of toxins that can specifically block single calcium channel types has made it possible to easily and rapidly discern the physiological roles of the different calcium channels in the neuron, Without these toxins it is unlikely that progress would have been as rapid.

• Molecules and Cells
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• v.42 no.8
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• pp.569-578
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• 2019

Transient receptor potential (TRP) channels are nonselective cationic channels, conserved among flies to humans. Most TRP channels have well known functions in chemosensation, thermosensation, and mechanosensation. In addition to being sensing environmental changes, many TRP channels are also internal sensors that help maintain homeostasis. Recent improvements to analytical methods for genomics and metabolomics allow us to investigate these channels in both mutant animals and humans. In this review, we discuss three aspects of TRP channels, which are their role in metabolism, their functional characteristics, and their role in metabolic syndrome. First, we introduce each TRP channel superfamily and their particular roles in metabolism. Second, we provide evidence for which metabolites TRP channels affect, such as lipids or glucose. Third, we discuss correlations between TRP channels and obesity, diabetes, and mucolipidosis. The cellular metabolism of TRP channels gives us possible therapeutic approaches for an effective prophylaxis of metabolic syndromes.

• Journal of Korean Neurosurgical Society
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• v.42 no.3
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• pp.205-210
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• 2007

Objective : Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels mediate the hyperpolarization-activated currents (Ih) that participate in regulating neuronal membrane potential and contribute critically to pacemaker activity, promoting synchronization of neuronal networks. However, distinct regional and cellular localization of HCN channels in the brain have not been precisely defined. Aim of this study was to verify the precise cellular location of HCN1 channels in rat cerebellum to better understand the physiological role these channels play in synaptic transmission between CNS neurons. Methods : HCN1 expression in rat brain was analyzed using immunohistochemistry and electron-microscopic observations. Postsynaptic density-95 (PSD-95), otherwise known as locating and clustering protein, was also examined to clarify its role in the subcellular location of HCN1 channels. In addition, to presume the binding of HCN1 channels with PSD-95, putative binding motifs in these channels were investigated using software-searching method. Results : HCN1 channels were locally distributed at the presynaptic terminal of basket cell and exactly corresponded with the location of PSD-95. Moreover, nine putative SH3 domain of PSD-95 binding motifs were discovered in HCN1 channels from motif analysis. Conclusion : Distinct localization of HCN1 channels in rat cerebellum is possible, especially when analyzed in conjunction with the SH3 domain of PSD-95. Considering that HCN1 channels contribute to spontaneous rhythmic action potentials, it is suggested that HCN1 channels located at the presynaptic terminal of neurons may play an important role in synaptic plasticity.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.45 no.3
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• pp.163-172
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• 2022

The development of ICT technology has created new channels for product sales and promotion, which not only make information accessible to customers as easy as possible, but also provide consumers with much more absolute and comparative information. Modern consumers are exposed so many shopping channels currently, especially mobile-based channels have grown significantly and have become the center of the market. It is true that mobile shopping has led the growth of overall online shopping with the recent development of mobile devices such as smartphones and related software. The importance of strengthening corporate competitiveness and mobile-based management strategies through on line channels continues to increase. At this point, this study attempted to investigate the influencing factors by focusing on the entire distribution channel and mobile shopping channels. As most of previous studies were focused on Internet shopping malls or specific channels, So the research on mobile channels can be judged to be timely and appropriate. Furthermore, it can be said that mobile shopping channels are now presenting empirical implications. In conclusion, it provides practical implications to examine the management strategy of mobile shopping channels from the perspective of consumer value.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.1
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• pp.59-64
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• 2008

Micro machining can manufacture complex shapes with high accuracy. Especially, this enables wide application of micro technology in various fields. For example, micro channels allow fluid transfer, which is a widely used technology. Therefore, liquidity research of flow in micro channels and micro channel manufacturing with use of various materials and cutting conditions has very important meaning. In this study, to find out correlation between fluid velocity in micro channels and surface roughness, we manufactured micro channels using micro end-mill and dropped ethanol into micro channels. We compared several surface roughness and fluid velocity in micro channels that were created by various processing conditions. Finally, we found out relationship between fluid velocity and surface roughness in micro channels of different materials.

• International Commerce and Information Review
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• v.10 no.2
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• pp.235-261
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• 2008

The purpose of the study is to test differences in consumers' satisfactions on products' competitiveness by domestic distribution channels of foreign clothing brands. Domestic distribution channels of foreign clothing brand consist of 5 channels as multi channel strategy. And product's competitiveness consists of prices, qualities, brand image and services. The results from the research show that there are differences in satisfaction by distribution channels. And they imply that distribution channel strategy is used with 5 channels in Korea, which are emphasized with different products' competitiveness. The contribution of the study is to analyze differences in consumer's satisfaction by 5 channels with data from consumer's perspectives, not firms' viewpoints.

• Korean Journal of Acupuncture
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• v.30 no.4
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• pp.305-318
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• 2013

Objectives : The aim of this study was to examine the effect of electroacupuncture(EA) at an acupoint, HT8(Sobu), on normal humans by using power spectral analysis. We examined the effect on the Heart Rate Variability(HRV), and the balance of the autonomic nervous system. Methods : Thirty-two healthy volunteers participated in this study. EEG(Electroencephalogram) power spectrum exhibits site-specific and state-related differences in specific frequency bands. A thirty-two channel EEG study was carried out on thirty-two subjects(14 males; mean age=23.5 years old, 18 females; mean age=21.5 years old). HRV and EEG were simultaneously recorded before and after acupuncture. Results : In the ${\alpha}$(alpha) band, during the HT8-acupoint treatment, the power values in the ${\alpha}$(alpha) band significantly decreased(p<0.05) at 28 channels. In the ${\beta}$(beta) band significantly decreased(p<0.05) at 26 channels. In ${\delta}$(delta) band significantly decreased(p<0.05) at 18 channels. In ${\theta}$(theta) band significantly decreased(p<0.05) at 20 channels. ${\alpha}/{\beta}$ values were increased at 6 channels and decreased at 10 channels.${\beta}/{\theta}$ values were increased at 10 channels and decreased at 19 channels. Mean-RR(RR-interval), Complexity, RMSSD(Root mean square of successive differences), SDSD(Standard deviations differences between adjacent normal R-R intervals), norm HF showed a significantly increased and mean-HRV, norm LF, LHR(LF/HF Ratio) showed a significantly decreased after HT8-acupoint treatment(p<0.05). Conclusions : These results suggest that EA at the HT8 mostly causes significant changes on alpha(28 channels), beta(26 channels), delta(18 channels), theta(20 channels) bands and mean-HRV, mean-RR, complexity, RMSSD, SDSD, norm LF, norm HF and LHR. If practicing EA at the HT8, it will regulate the function of the cerebral cortex, decrease activity of the sympathetic and increase parasympathetic nervous activity.

• The Korean Journal of Physiology and Pharmacology
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• v.5 no.2
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• pp.147-156
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• 2001

It has been proposed that $Ca^{2+}-activated$ K $(K_{Ca})$ channels play an essential role in vascular tone. The alterations of the properties of coronary $K_{Ca}$ channels have not been studied as a possible mechanism for impaired coronary reserve in cardiac hypertrophy. The present studies were carried out to determine the properties of coronary $K_{Ca}$ channels in normal and hypertrophied hearts. These channels were measured from rabbit coronary smooth muscle cells using a patch clamp technique. The main findings of the present study are as follows: (1) the unitary current amplitudes and the slope conductance of coronary $K_{Ca}$ channels were decreased without changes of the channel kinetics in isoproterenol-induced cardiac hypertrophy; (2) the sensitivity of coronary $K_{Ca}$ channels to the changes of intracellular concentration of $Ca^{2+}$ was reduced in isoproterenol-induced cardiac hypertrophy. From above results, we suggest for the first time that the alteration of $K_{Ca}$ channels are involved in impaired coronary reserve in isoproterenol-induced cardiac hypertrophy.

• Animal cells and systems
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• v.11 no.2
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• pp.199-204
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• 2007

HCN (hyperpolarization-activated cyclic nucleotide-gated) channels, whose gene family consists of four subunits (HCN1-4), mediate depolarizing cation currents and contribute to controlling neuronal excitability. In the present study, immunohistochemical and electrophysiological approaches were used to elucidate the role of HCN channels in the cerebellum. Immunohistochemical labeling for HCN1 and HCN2 channels revealed localized expression of both channels at pinceau, the specialized structure of presynaptic axon terminals of basket cells. To determine the functional role of the presynaptic HCN channels, spontaneous inhibitory postsynaptic currents (IPSCs) were recorded from Purkinje cells, the main synaptic targets of basket cells in the cerebellum. While activation of HCN channels by 8-bromo-cAMP increased amplitude of spontaneous IPSCs, blockade of the activated HCN channels by subsequent ZD7288 application reduced the amplitude of spontaneous IPSCs to the level far below the control. Our results imply that modulation of HCN1 and HCN2 channels in presynaptic terminals of basket cells regulates neurotransmitter release, thereby controlling the excitability of Purkinje cells.